Localization devices have been developed to assist surgeons in performing surgical procedures. When utilized in a procedure, markers that are observable by a stereoscopic sensor system are attached to bones. The sensor system is connected to a data processing system that records the positions of the markers in space to establish a coordinate reference system relative to each bone bearing a marker. Additional markers may be mounted on surgical tools used to palpate (touch) specific landmarks on the bones while the system records their location in order to ascertain the position of the landmarks in the coordinate reference systems of the bones. Additional markers also may be mounted on surgical tools used to perform the procedure in order to monitor the position of the surgical tools during the procedure. The localization device is preprogrammed with information regarding the position and orientation of the working portion of the tool relative to the marker. Thus, by tracking the marker mounted on the tool, the localization device is able to track the tool itself. A monitor is used to display information developed from the coordinate reference system, the landmarks, and the monitored positions of the surgical tools for use in guiding a surgeon during the procedure, such as navigating a surgical tool to a particular location in the coordinate reference system.
During a surgical procedure, the position and orientation of a surgical tool being navigated by the localization device may be determined for use later in the procedure and/or for post operative analysis. As noted, the position and orientation of the surgical tool are determined by observing a marker mounted on the surgical tool. The marker can be mounted on the surgical tool in only one predetermined way and the localization device is preprogrammed with data indicating the orientation and position of the surgical tool relative to the marker. By observing the marker, the localization device can determine the position and orientation of the surgical tool. Typically, the coordinates of the observed marker are captured and stored in a memory associated with the localization device in response to a designated event, e.g., the actuation of a switch by the surgeon.
The accuracy of the position and orientation of the surgical tool as determined by the localization device is dependent on several factors. These factors include proper mounting of the marker on the surgical tool, accurate preprogramming of the data indicating orientation and position of the surgical tool relative to the marker, and trueness of the marker and surgical tool. If any of these factors are amiss, the position and orientation of the surgical tool as determined by the localization device will be erroneous.
Accordingly, there is a need for capturing information to verify the orientation and position of a surgical tool being navigated by a localization device. The present invention fulfills this need among others.